Abstract
According to well-known biochemical and biophysical mechanisms, the stimulation of C(3) photosynthesis by elevated atmospheric CO(2) concentration ([CO(2)]) is strongly modified by changes in temperature and radiation. In order to investigate whether a static parameterization of the commonly used Farquhar et al. model of photosynthesis (i.e., without CO(2)-induced seasonal or thermal acclimation of photosynthetic capacity) can accurately predict these interactions in mature boreal Norway spruce (Picea abies (L.) Karst.) during the frost-free part of the growing season, shoot gas exchange was continuously measured on trees during their second/third year of exposure to ambient or doubled [CO(2)] inside whole-tree chambers. The relative CO(2)-induced enhancement of net photosynthesis (A(n)) at a given temperature remained stable over the study period, but increased strongly with temperature and radiation, in agreement with predictions by the model. Light-saturated A(n) (+67% at 20 °C), dark respiration (+36%) and intercellular to ambient [CO(2)] ratio (c(i)/c(a); +27%) were significantly increased by CO(2) treatment. Stomatal conductance (g(s)) was not significantly affected. Our results demonstrate that the Farquhar et al. model of photosynthesis has the capability to predict interactions between [CO(2)] and seasonal weather variability on A(n) in Norway spruce during the non-frost growing season without accounting for CO(2)-induced seasonal and/or thermal photosynthetic acclimation. However, stomatal model assumptions of reduced g(s) and constant c(i)/c(a) under rising atmospheric [CO(2)] did not hold.
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Claims 8
Claim · model-written summary
Relative CO2 enhancement of photosynthesis was stable over the study period at a given temperature.
- Taxon
- Norway spruce
Picea abiest0 - Outcome
- net photosynthesise0
- Direction
- remained stablee0
- Qualifier
- at a given temperaturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The relative CO(2)-induced enhancement of net photosynthesis (A(n)) at a given temperature remained stable over the study period”
t0“Norway spruce”
Claim · model-written summary
Relative CO2 enhancement of photosynthesis rose with temperature and radiation.
- Taxon
- Norway sprucePicea abiest0
- Treatment
- temperature and radiatione0
- Outcome
- net photosynthesise1
- Direction
- increasede0
- Qualifier
- temperature and radiatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased strongly with temperature and radiation, in agreement with predictions by the model”
t0“Norway spruce”
e1“net photosynthesis (A(n))”
Claim · model-written summary
Doubled CO2 increased light-saturated net photosynthesis by 67% at 20 °C.
- Taxon
- Norway sprucePicea abiest0
- Treatment
- CO(2) treatmente0
- Outcome
- Light-saturated A(n)e0
- Direction
- increasede0
- Value
- +67%e0
- Qualifier
- at 20 °Ce0
- Comparator
- ambiente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Light-saturated A(n) (+67% at 20 °C), dark respiration (+36%) and intercellular to ambient [CO(2)] ratio (c(i)/c(a); +27%) were significantly increased by CO(2) treatment”
t0“Norway spruce”
e1“ambient or doubled [CO(2)]”
Claim · model-written summary
Doubled CO2 increased dark respiration by 36%.
- Taxon
- Norway sprucePicea abiest0
- Treatment
- CO(2) treatmente0
- Outcome
- dark respiratione0
- Direction
- increasede0
- Value
- +36%e0
- Comparator
- ambiente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Light-saturated A(n) (+67% at 20 °C), dark respiration (+36%) and intercellular to ambient [CO(2)] ratio (c(i)/c(a); +27%) were significantly increased by CO(2) treatment”
t0“Norway spruce”
e1“ambient or doubled [CO(2)]”
Claim · model-written summary
Doubled CO2 increased intercellular to ambient CO2 ratio by 27%.
- Taxon
- Norway sprucePicea abiest0
- Treatment
- CO(2) treatmente0
- Outcome
- intercellular to ambient [CO(2)] ratioe0
- Direction
- increasede0
- Value
- +27%e0
- Comparator
- ambiente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Light-saturated A(n) (+67% at 20 °C), dark respiration (+36%) and intercellular to ambient [CO(2)] ratio (c(i)/c(a); +27%) were significantly increased by CO(2) treatment”
t0“Norway spruce”
e1“ambient or doubled [CO(2)]”
Claim · model-written summary
Stomatal conductance was not significantly affected by CO2 treatment.
- Taxon
- Norway sprucePicea abiest0
- Treatment
- CO(2) treatmente1
- Outcome
- Stomatal conductancee0
- Comparator
- ambiente2
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal conductance (g(s)) was not significantly affected”
t0“Norway spruce”
e1“CO(2) treatment”
e2“ambient or doubled [CO(2)]”
Claim · model-written summary
The Farquhar model predicted CO2 by seasonal weather interactions in spruce photosynthesis without acclimation.
- Taxon
- Norway sprucePicea abiese0
- Outcome
- predict interactions between [CO(2)] and seasonal weather variability on A(n)e0
- Qualifier
- without accounting for CO(2)-induced seasonal and/or thermal photosynthetic acclimatione0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the Farquhar et al. model of photosynthesis has the capability to predict interactions between [CO(2)] and seasonal weather variability on A(n) in Norway spruce during the non-frost growing season without accounting for CO(2)-induced seasonal and/or thermal photosynthetic acclimation”
Claim · model-written summary
Stomatal model assumptions of reduced conductance and constant CO2 ratio did not hold.
- Taxon
- Norway sprucePicea abiest0
- Outcome
- stomatal model assumptionse0
- Qualifier
- under rising atmospheric [CO(2)]e0
- Comparator
- reduced g(s) and constant c(i)/c(a)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal model assumptions of reduced g(s) and constant c(i)/c(a) under rising atmospheric [CO(2)] did not hold”
t0“Norway spruce”
The same questions in other papers
co2 · physiology: gas exchange · Picea abies (Norway spruce)Positive and negative results
3 papers in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
- no effect
1 paper more in this group
See all 5 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.